I did it many times, sometimes the fishing was really good, sometimes not so good. Some of the lakes have self supporting populations of trout, some of them need to be stocked periodically with fingerlings. General rule of thumb was the further you hike in, the better the fishing is. The fish usually top out in the 14-16 inch range as the only food for them is insects and they can't grow much larger than that on a diet of bugs. If a person had a week or two to spend hiking and fishing, with a little planning and picking the right trail you could fish a different lake every day on the hike.